France to Germany is an intra-Schengen journey so you would not have access to the lounge mentioned in this thread, which is for Paris to London services only.
It's a bit confusing because they are now all called Eurostar, but formerly you would have been on a "Thalys" train.
You will be able to use a lounge about 1 minute walk west outside of GdN station, but I don't believe alcohol is available at any time (not 100% sure).
You are correct. Tea, coffee, water, juice, and minuscule sweet snacks.